


The Question of Expendability

by Geekthefreakout



Category: Supernatural
Genre: Casifer, Destiel - Freeform, M/M
Language: English
Status: In-Progress
Published: 2016-02-10
Updated: 2016-02-23
Packaged: 2018-05-19 11:17:30
Rating: Teen And Up Audiences
Warnings: No Archive Warnings Apply
Chapters: 3
Words: 4,584
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/5965309
Author URL: https://archiveofourown.org/users/Geekthefreakout/pseuds/Geekthefreakout
Summary: <blockquote class="userstuff">
              <p>Having realized the Castiel is possessed by Lucifer, Sam and Dean search for a way to free him. They think they may have one, but it comes with risks- to more than just them and Cas. All leading to the question- Can they risk the world for their friend? This is a gift for my friend Lydia! She's awesome.</p>
            </blockquote>





	1. Finding an Answer

     Dean had been praying almost non-stop for the past two weeks. He didn't know if Cas could hear him- but then, Cas always heard him, didn't he? He said so himself, even if he couldn't always answer. Dean had to believe that Cas was in there somewhere, that Lucifer hadn't killed him or swallowed his grace up. The alternative… Dean wouldn't let himself think of it. So any spare moment he had when he wasn't searching for some way to crowbar Lucifer out of Cas' vessel. He ran his hand through his hair as he flipped through yet another book- he must have gone through a quarter of the Men of Letters' rather extensive library by now, and he'd found exactly bubkis.

     “Are you still in here?”

     Dean's head snapped up as Sam came into the room with two plates in hand.

     “I'm gonna be here until we find something. We have to save Cas.”

     “Yeah, I'm not arguing that. It's just...” Sam slid into the seat across from Dean, placing a plate on top of the book Dean was reading. “You haven't budged in hours. You still need to eat and sleep, you know.”

     “Yeah, whatever.” Dean rubbed his fingers roughly over his eyes. “I just don't get it, man. Lucifer still needs permission to possess someone, right? I don't understand why Cas would let him in, I really don't.”

     “I don't get it either,” Sam said, taking a bite of his burger. “But then, Cas hasn't really been in the best state mentally lately, have you noticed? Lucifer must have got to him somehow- I know first hand how manipulative he can be.”

     Dean broodingly bit into his own burger, barely tasting it. All he could think about was his Lucifer's demented grin corrupting Cas' familiar face, after Dean had realized that Cas was no longer in control of his body.

_Dean looked up as Cas entered the library, frowning as he watched the angel stride- swagger, almost- to the bookshelf that held the inventory for all the odds, ends, and magical objects held in the Men of Letters bunker. This was the second time that Dean had seen Cas and thought something was off about him. He didn't think Cas was actively hiding anything from him- he wasn't acting quite squirrely enough for that- but there was something in the way he spoke, in the way he moved, that was just barely off-color._

_“_ _You ok, Cas?” he asked. Cas turned to him with a smile that was just a breath too wide, casually closing the distance between them until they were only inches apart._

 _“_ _I'm fine, Dean._ _You don't have to worry about me.”_ _They were standing so close that Dean could feel Cas' breath on his face, could feel the heat emanating from his body. It was just the tiniest bit closer than Cas usually stood,_ _the kind of close that made it nearly impossible for Dean not to stare at Cas' lips, the kind of close where the temptation to close the distance entirely was at its strongest._ _The kind where the niggling concern in the back of his head that something was very, very wrong was silenced by the proximity._

 _“_ _I know, bud, it's just that you've been a little distant lately. You could stand to answer your phone once and a while.”_ _Dean_ _chided. Cas' smile widened as he leaned closer, one hand coming up to Dean's shoulder._

 _“I'm sorry to have worried you,” he whispered,_ _and suddenly his nose was brushing against Dean's, and his breath was on Dean's lips, and it was everything Dean had ever wanted._ _Cas' lips were teasingly brushing over his, and he leaned forward to deepen it into a proper kiss- then Cas' hand tightened on his shoulder, and the niggling concern turned into alarm bells. Dean shoved back with all_ _8_ _his might, but Cas- or whatever was currently wearing Cas' meat- did not seem particularly inclined to move. He simply drew his head back an inch so that Dean could see his full face._

 _“_ _Is something the matter, Dean?” Not- Cas asked, and Dean didn't know how he didn't see it clearly before._ _Not- Cas' eyes, usually full of a fondness that Dean was often uncomfortable acknowledging, were cold and cruel. His mouth was twisted in a parody of Cas' usually_ _small grin, and his hand was clamped tightly to Dean's shoulder- the wrong shoulder, Dean thought. It was so strange that there was such a thing as the wrong shoulder, but Cas had always, unerringly, clapped his hand down on the arm that used to bear his mark._ _This last observation gave Dean the strength to rip his arm free and move back._

 _“You're not Cas, you son of a bitch. Who are you?”_ _He snarled. Not- Cas' eyes widened._

_“Dean, I really don't know what you… ah, well. I definitely had you going there for a bit though, didn't I?” Not- Cas chuckled and allowed his tiny smirk to become a full on sadistic grin- one that Dean almost found familiar. “Go on- what was it that gave me away, Dean-o? I thought I was doing a pretty good impression of my little brother.”_

_Dean felt his heart drop into his stomach, and his brain suddenly felt as though it was filled with static._

_“No… you're not, you can't be,” he stammered, fists clenching spastically._

_“Oh, I can.” Lucifer grinned. “I am.”_

     Dean shook himself out of his memories and took a swig of his beer. Lucifer had disappeared shortly after revealing himself, but Dean was certain he'd come back while they were out trying to find him. Things in the library had been out of place, and one of the dungeon doors had been left open, leading Sam and Dean to reluctantly ward the bunker against angels entirely.

    “We'll have to fix it when we get Cas back.” Sam had said while he was painting sigils across the door. Dean had nodded, unable to get any words past the lump in his throat.

    “What makes you so sure there are angelic exorcisms, anyway?” Sam asked, once again snapping Dean back to the present. “I mean, if there were such a thing, wouldn't Cas have done it when I was possessed by Gadreel? That must be safer than sending freakin Crowley in after me.”

    “Not if he didn't know it… say, Crowley. That's an idea.” Dean replied speculatively as he finished off his meal. As King of Hell- as a demon- Crowley had access to spells and incantations that may not be in the Men of Letters library… especially considering that Dean was growing more and more certain the spell that he had in mind was demonic in origin.

    “Wait, why is Crowley an idea?” Sam scowled. “It's not anything but a _bad_ idea, Dean, whatever you're thinking.”

    “No, listen- You remember back before the apocalypse started? Pamela had just died, and Cas showed up with Uriel--”

    “Because they'd captured Alistair and wanted you to torture, him. I remember.” Sam's scowl deepened as he remembered the week Dean had spent in the hospital afterward, recovering from Alistair's assault. “What about it?”

    “Before you came in all juiced up-” Dean shot an apologetic look at Sam, “Alastair had Cas pinned. I was pretty much out of commission, but I could still hear what was going on. Alastair said that he couldn't kill angels, all he could do was send them back to heaven. He started this chant, and it sounded like Cas was having trouble. Then you came in and I passed out.”

    “Okay, fine, so the angelic exorcism probably exists. That means we probably have it here somewhere.” Sam said, getting up to pull another book from the shelf.

    “I looked in that one already.” Dean said, pulling the book away from his brother. “And if it's something the demons made up- we might not have it. The lore we have on angels is spotty at best, anyway-- Remember how Cas threw out like five books because they were full of nonsense?”

    “Alright, fine, say you're right. What makes you think Crowley would help us? We haven't heard jack from him since we left Hell. He might have thrown in with Lucifer- or Lucifer could have killed him. I'm sure he remembers who helped us take him down last time.”

    “We won't know until we try. Besides, Crowley hasn't thrown in with Lucifer.” Dean said with certainty.

    “And how do we know that?” Sam asked, throwing his arms out in exasperation. Dean smiled.

    “Because that's what his mother would want him to do.”


	2. On the Road

    Crowley sounded relieved when he finally answered his cell phone.

    “Hello, boys. I think I can guess the reason for this booty call.”

    “You son of a bitch, you knew?” Dean snarled at the phone resting on the table in the war room.

    “Well, it was hard to miss after he strolled in here and snapped Mother’s pretty neck.” Crowley drawled. “It put him in a good enough mood that he didn't bother with me, and I made myself scarce afterward.”

    “Rowena's dead?” Sam checked, leaning forward. Dean, on the other hand, couldn't care less about a dead witch.

    “And it didn't occur to you that _maybe_ we should know that Cas is possessed by the freakin' _devil?_ For almost a _month_?”

    “It occurred.” Crowley said irritably. “But I had to look out for Crowley, and that meant that I had to wait for you two knuckleheads to work it all out. Lucifer let me live once- I doubt he'd be so charitable if I blew his cover. And yes, Mother is dead. Ding dong, and all that.”

    “Great to know where your loyalties lie.” Dean sneered, pacing back and forth. Crowley's sigh blew static across the connection.

    “My loyalties lie exactly where they always have- with myself. It's not that I don't adore you, Squirrel. I just love myself more. At any rate, I certainly didn't think it would take you this bloody long for you to realize your boyfriend was out of sorts. Now, I assume you have a plan of some sort, because if not I'm going to have to kindly ask you to bug off before Lucifer gets it in his head to track me down.”

    Sam glanced up at his brother, who was red-faced and glaring at the phone, and decided to take over before Dean's temper lost them their demon up their sleeve.

    “We were wondering what you might know about angelic exorcisms.”

    Crowley was quiet for a moment.

    “I know of them. I think I might know what you have in mind.” There was a hint of hesitation in Crowley's voice. “I think we'd be better off discussing this in person. More secure, you understand.”

    “Yeah, okay. Where?” Dean asked, already grabbing the keys for the Impala. Crowley spouted off an address about a half day's drive away from the bunker and hung up, clearly in a rush.

    “Just so we're clear, I'm iffy on this.” Sam said, even as he pulled on his boots and followed his brother towards the car. “Lucifer must know that Crowley worked against him during the Apocalypse, sat on a throne while he was stuck in the Cage. That he's still breathing air without having offered Lucifer something is sounding pretty far-fetched to me.”

    “Crowley does what he has to do to keep kicking, but I guarantee you he still wants Lucifer gone.” Dean said, sliding into the driver's seat. He turned on the heat against the winter chill and listened a moment to the legos rattling in the vents. “Look, if it goes sideways, we'll deal with it. But right now this is our best chance at helping Cas. That has to be our priority here.”

    “Dean, I get you. I want to help Cas too, he's my friend. But I know he wouldn't want you getting yourself hurt or killed trying to help him, you know? I just want you to be smart about this.”

    “I'm always smart.” Dean started driving, lips drawn tight. Sam scoffed.

    “Not about this, you're not. Not about family. You get dumb about Cas almost as much as you get dumb about me. You take risks, you don't think things through.”

    “Spent two weeks looking for another way, Sam. That's two damn weeks with Cas trapped in his vessel by that douchewad while we were 'thinking things through.' This is the plan now, it is our only plan, and we are going to follow through on it. We owe it to Cas.”

    They drove in silence for a while, with no sound between them but the hum of engine and the rattling of the legos. Dean's knuckles were white where they were clutched over the wheel, the muscle in his jaw spasming each time he felt Sam glance at him. Finally Sam heaved one of those sighs that meant he wanted to have some kind of heart to heart. Dean hated that sigh.

    “Dean.”

    Dean didn't respond except to turn on the radio. Sam sighed again.

    “Dean _._ ”

    The music got louder, until the opening guitar riffs of “Bat Out of Hell” were vibrating in Sam's chest. He reached over and turned it off.

    “ _Dean._ ”

    Dean yanked violently on the steering wheel, pulling over to the shoulder of the highway.

    “ _What_?” He snarled, whipping around to glare at his brother. Sam met his gaze steadily, recognizing the wild look in his eyes that only emerged when one of the few people that held a piece of his heart was in danger.

    “There's something else we have to consider about this situation.”

    “You still going on about Crowley? Because I swear we've covered that ground already.”

    “No, not about Crowley. About Cas.” Sam allowed that to hang in the air between them for a moment. He knew that what he had to say next would not be received well, but he also knew it had to be said. “There's a chance he might not _want_ us to free him. No, shut up, I've been thinking about this.” Sam held up a hand to stave off Dean's furious look. “Lucifer couldn't enter Cas' body without consent. All I'm saying is that I wouldn't put it past Cas to allow him in for no reason other than us needing him to fight Amara. And for that same reason, he might not want to get rid of him.”

    “That's bullshit. Cas knows we need him, and he knows that Lucifer is full of it. No way he actually wants to be trapped in his meat suit, no way would he give Lucifer that power over him without some serious strings being pulled.” Dean glared at Sam, fists clenching in his lap.

    “Look, Dean, I'm not fond of the idea either, but the fact is, whatever the reason, Cas said _yes._ If he hasn't changed his mind about that, getting Lucifer out will only be harder. We have to consider it.”

    “Fine, it's considered. And it doesn't change anything. Let's get back on the road, I want to get to this place before midnight.”

    Dean started the car and turned the music back up as they pulled back on to the road, and Sam knew the conversation was over for now. Dean wouldn't pay attention to this matter until he had no other choice. It was how he always dealt with disasters in the family. Dad was fine, until he wasn't. Sam was perfectly normal and good, until he wasn't. Cas was alive. Cas was on their side. Cas was coming back. Until he wasn't. So Sam leaned his head against the window and sent out a prayer of his own to Cas. 

_Please, please come back to my brother_.

    He only hoped that Cas would listen when he heard it.


	3. How Lucifer Fought

    Lucifer stood silently near a cave at the lowest point of the Grand Canyon. Distantly, he remembered the battle that had helped form this wonder of the world, one of the earliest battles against the Darkness. That was when he was still a young angel, before many of his brothers and sisters had been created. It had only been his Father and his fellow archangels, standing shoulder to shoulder against the chaos that was the Darkness. He had been the favored son then, the Morningstar, with his eight strong, shining wings beating in the air of a new Earth. The battles had changed the shape of the planet and raged across the stars.

    And now here he was, facing this creature once again. It was not out of loyalty to his Father (wherever he had flapped off to), or to his brothers ( _dead_ , he thought with a twinge of remorse, excepting Michael who was in no state to fight), or to the planet (he could always find a new one, now that he was free of that thrice-damned cage). No, he was eager to battle the Darkness for himself, for survival (surely she would come for him eventually) and for revenge. His now-blackened wings rippled in agitation at the thought. In his vessel, he felt a twinge of curiosity from his host. Poor Castiel- one of his youngest brothers, Lucifer had borne witness to his creation but had not interacted with him while he had still been welcome in heaven. Lucifer decided to humor Castiel as he walked in to the cave.

_Much happened before your existence began, little brother._ _We were happy, once._ Lucifer explained, biting his finger and rubbing blood across a sigil on the floor of the cave. The sigil lit up with ancient grace and Lucifer remembered…

    He remembered his Father's voice, His light, strong enough to destroy stars and create them anew as he argued with his Sister. He remembered perching inside a nebula with his brothers and watching his Father forge his first weapons, remembered Michael clutching anxiously at the stardust around them and Gabriel holding tight to his wings to stop him from bursting out and revealing himself to Father. (Father, of course, had known they were there, but they had been so young, and the tiny hint of rebellion was endearing then.) Father wanted to protect them at first- he battled the Darkness alone for thousands of years as the molten rock that was the Earth began to cool and life first emerged. To keep them occupied while he was away, he had given each of them a ball of Light and instructed them to design creatures to inhabit the new planet. During lulls in the battle, Father would return and review their designs. Those He liked received Life and were given a part in the Great Plan. Lucifer himself had designed dinosaurs. He'd wanted his creatures to be huge, far bigger than Raphael's spiders or Gabriel's platypus (Gabriel was always strange). Father had laughed when he showed Him his design, chided him gently for his hubris in making something so large, but breathed Life into them anyway.

    Still, the war between God and the Darkness did not abate. When Father began to create the lesser angels- younger brothers and sisters for the archangels to look after and help raise, the Darkness answered with the Leviathan. Lucifer recalled with a shudder how the first batch of new angels had been decimated by the creatures while Father's attention was devoted elsewhere. Only one had survived- scrawny little Metatron. Father's wrath had been mighty that day. Michael had shielded Metatron with his wings while Raphael and Gabriel looked on in horror, but Lucifer had been ready to fight from then on.

    “They were my brothers and sisters, Father, as well as your children,” he'd pleaded while God created Purgatory and locked the Leviathan away there. “Let me help you- Let Michael and I be your sword and shield, and we shall not let you down.”

    Finally, God agreed. The four archangels went to battle with their Father, and it was a battle that raged across the cosmos. One particularly momentous engagement had shattered the planetoid that became Saturn's rings. Sometimes the Darkness would retreat for centuries, and life on Earth would blossom. Father made a million lesser angels, and set his great plan for Life in motion. During the last of these lulls, Lucifer got to see his dinosaurs walk the Earth. They were large and beautiful and varied and Lucifer often took his younger siblings down to perch on the mountains and watch them live. He and Uriel loved to play with the long-necked Brachiosaurs, and to fly along side the winged Pterodactyls, using their own wings to create gusts of wind that would blow the pterodactyls off course- but only for a moment, because Lucifer's dinosaurs were strong and would always right themselves in moments. Michael often chided him for thinking in such possessive terms.

    “They are Father's creatures, Lucifer. You did not give them Life.” How many times had he heard this phrase repeated at him, first from Michael, and then from that suck-up Raphael? Gabriel never nagged him so, but that was likely because he was busy badgering Father about the state of the platypus and when would it be his turn to see his designs come to life? Father used to laugh at Gabriel and tell him to be patient.

    When the peace ended, it ended with fire. The Darkness returned with a vengeance, and the archangels went to war again. Lucifer recalled watching in despair as she hurled a huge, blazing meteor at the Earth with one hand while holding Michael's wings in the other. Lucifer had been faced with a choice- his brother or his dinosaurs. He and Father had moved together to save Michael from the Darkness, of course (because he loved Michael, in spite of everything), but the dinosaurs were wiped from existence. He and Gabriel had left Raphael with their Father while they carried Michael to a spot behind the moon where he could heal, and Lucifer had raged at the destruction of his creations. He hurled his own meteors, pummeling the surface of the moon until it was covered in craters. As soon as Michael was stable, he flung himself back into battle, wings blazing as bright as the sun, and the darkness knew Lucifer's wrath that day. He fought and clawed and shocked even Father with his fury. Finally, after the Darkness had pushed their line right back to Earth's atmosphere, Father had taken him aside.

    “She hurt our world, Father.” Lucifer said plaintively. “She destroyed my dinosaurs, which I created and you breathed Life into. I will not stop until she does.”

    “Yes, my son. And she will never stop.” Father sighed and stroked a hand along Lucifer's mighty wing. “I think I might have a way. I have created a curse that will contain my sister, seal her away forever. But seals must have keys, and this one will be a great burden to carry.”

    “Surely not too great for you, Father.” Lucifer objected.

    “Perhaps;” Father said. “But perhaps not. I am not meant to bear it, Lucifer.” And Lucifer stretched his wings out to their fullest extent, puffed his chest and said proudly-

    “Then I will bear it for you, Father.” And his Father smiled at him and began to explain his plan.

    … Lucifer returned to the present as the grace from the sigils faded to reveal a collection of holy weapons. Tentatively he reached for a great spear, hefted it in his vessel's hands… but it was not as mighty a weapon as it once was. It had been one of Michael's favored weapons, he thought, before he'd settled on the use of a sword. Within him, Castiel pressed his little grace forward, alight with curiosity. The seraph had not come across this weapon during his foolish war with Raphael.

_Many of the weapons in our fight against the Darkness were not secured in Heaven_ , Lucifer explained charitably. He frowned. The spear did not have as much power as it had in ancient days. He didn't know if it would be enough. He laid it to the side and reached for another weapon, this time a pearl the size of a tennis ball that once held a piece of God's own light. The light was dim, now. Perhaps it had lost it's power when God had abandoned the Earth.

_Father…_ Castiel's grace sang sadly. Lucifer shoved him down, further into the vessel. What right did this seraph have to mourn the absence of their Father? He'd never met him, never known him… never even laid eyes on him. After the Darkness had been sealed away, God had withdrawn from all but his oldest children. The archangels, and little Metatron (that was another suck up- a lesser angel who thought himself far more important than he was), who became his scribe, were all that were permitted in his presence. It became the duty of the archangels to pass orders along from their Father to their siblings. Lucifer remembered very clearly the day Gabriel was told his platypus would soon come in to being. The archangel had been trembling with excitement and spiraled quickly down to the surface of the planet with one of the little brothers he was closest to to watch the platypus begin.

_Don't step on that fish, Castiel. Big plans for that fish._ A memory stirred from his host. One of Castiel's earliest memories, and it had to do with the platypus, of all things. Gabriel would be pleased to be so remembered.

    Finally, Lucifer unearthed a box which held a seed and a bit of dirt. He smirked- this could only be from the tree of knowledge in the Garden. It wasn't a weapon, per se, but as a source of power (his smirk widened when he realized it's holiness had not faded with time) it would be quite valuable. He stuffed it in the pocket of Castiel's ridiculous trench coat and exited the cage. There were other weapons, he knew, lost to the sands of time, some collected by upstart humans or demons who knew to ward against angels… but hardly inaccessible. Perhaps it was time to pay the Winchesters a call in that regard...

    Castiel thrashed inside him angrily, ever protective of the two mud-monkeys he had sacrificed so much for. The seraph had taken particular umbrage at Lucifer's interaction with Dean Winchester- a violation of Dean's personal space, he'd said, an unfair deceit. _My vessel is not for you to torment him with,_ Castiel had insisted, pulling with all the might he had. Lucifer had settled for delighting in the look on Dean's face when he realized that his precious Cas wasn't himself before flying off to ponder the feelings emanating from the angel hosting him. A sense of possessiveness, that Lucifer's game had not just been a violation of Dean's space but also of something that _belonged_ to Castiel, a sense of anger (almost rage) that Lucifer had used Castiel's body to touch Dean in a way that Castiel himself had never dared. Lucifer snorted.

_Ah, Castiel, do not fret. I have no intention of harming them…_ Lucifer reassured. Then he smirked inwardly. _Of course, even if I did… what precisely could you do about it?_

    Then, ignoring the thrumming ire coming from his host, Lucifer took wing. Sam and Dean had warded their bunker against him, but it was little matter. They had to leave sometime- he could wait.

**Notes for the Chapter:**

> This was originally meant to be much longer, but I felt it meandered too much, so I chopped it up. The rest of Lucifer's memories will appear in an as-yet unwritten chapter called "How Lucifer Fell" at some point later on in the story.


End file.
